When winter comes, animals resort to some of the weirdest behaviors to survive the cold weather. Hibernation is probably the most popular one, but some other techniques are a lot more interesting. For instance, red-toothed shrews reduce the size of their skull until the arrival of spring.
How do tiny shrews survive during winter?
These shrews are tiny creatures which are often mistaken for rodents, when they are actually more similar to moles. The coldness of winter is also a big threat for them, so they have to find ways to survive. Instead of hibernating, they shrink their skull by about 20 percent of its original size. As soon as the warm season returns, their skull also comes back to how it used to be.
Researchers cannot explain why shrews resort to such an extreme solution. However, they suspect a smaller brain and skull size helps them preserve energy. Their options are limited during winter, as they cannot migrate, nor can they hibernate. Also, their bodies don’t store too much fat, so they always need to hunt. Since the harsh weather doesn’t allow to do this, they needed to find something else to save them.
The skull shrinking conserves a lot of energy
The brain requires a lot of energy to function. Therefore, if the food sources are scarce, the brain quickly consumes the energy which has already been quite poorly stored. If the brain shrinks, the energy requirements are smaller, as well as the food demands. Researchers have also noticed how other organs reduce their size as well.
Researchers couldn’t exactly tell how the shrinking took place. The shrews they had captured followed indeed the pattern of a peak brain size during summer, skull reduction during winter, and regaining of the original size during spring. They noticed how, during the cold seasons, the shrews’ joints reabsorb tissue, causing the shrinking. This tissue starts regenerating when the warm seasons return, so the skull returns to its size.